Revision for Class Test

Hi all,
Just some gentle reminders:

1. Factors affecting rate of diffusion: Refer to points in notes to revise for the factors that affect the rate of diffusion.

2. Permeability of membrane: Affected by membrane present (visking tubing and dialysis tubings are partially permeable), as well as if membrane is heated (becomes fully permeable after heating)

3. Uptake and loss of water: For plant cells, uptake and loss of water involves the large central vacuole, which reduces change in water potential of cytoplasm. For animal cells, uptake and loss of water involves the cytoplasm, as a large central vacuole is absent. Hence, animals usually try to regulate extracellular fluid (fluid outside cells, eg blood) to ensure that water potential of the cells do not change too drastically, as cells may shrivel or burst.

4. Endosmosis & Exosmosis: Terms that are used only for cells, and not non-living membranes such as the dialysis tubing.